To preserve activity and/or stability, many medicaments particularly those for injection or infusion, are prepared in a powdered or lyophilized form and packaged in sterile containers, generally tightly sealed with a rubber stopper to permit reconstitution with the desired diluent, usually sterile water for injection or normal saline solution. Often, such medicaments are toxic, irritating or mutagenic, particularly when reconstituted, should they come in contact with exposed body tissue. Also, such medicaments are often expensive and present in measured dosage amounts. Thus, to a person whose function it is to reconstitute such medicaments, means for effecting reconstitution without spillage is highly desirable and often imperative.
Presently, reconstitution is generally accomplished utilizing a conventional single bore needle mounted on a conventional syringe. To withdraw the dilution fluid, the needle is inserted through a rubber stopper cap of a sterile container containing the fluid. Fluid is forcibly removed from the container by suction created by withdrawal of the syringe plunger. As liquid is withdrawn, a significant negative pressure is created within the bottle. The creation of this negative pressure thus requires that considerable pulling force be exerted on the syringe plunger to remove the diluent from the container. The application of such force increases the opportunity for the preparer to spill, contaminate, mismeasures or otherwise mishandle the diluent and/or syringe thereby wasting costly materials and time. Also, spillage on to skin of preparer will be potentially hazardous to his or her health. Further, the preparer is often required to make several such withdrawals during a given period, resulting in strained, and at times, injured muscles and/or nerves, particularly in the wrist and forearm area.
Likewise, dilution of a medicament utilizing a conventional needle/syringe method is cumbersome and difficult and can result in wasted or inaccurately reconstituted medicament. During the instillation procedure, the needle attached to the syringe containing the diluent removed from the first container, is inserted into and through the rubber stopper cap of the sterile container containing the medicament. The diluent is then injected into the medicament container by a pushing action on the plunger of the syringe. The introduction of the diluent into the container creates a significant positive pressure therein, making the introduction of the diluent progressively difficult as the pressure within the medicament container builds up. For example, the introduction of 25 ml of liquid into a 27.5 ml capacity bottle will compress air within the bottle such that the pressure within the bottle would be approximately ten atmospheres. In the usual practice, to prevent such a high pressure gradient from building up, repeated exchanges of smaller volumes of diluent for air between the medicament container and syringe are made. This process is likewise cumbersome and time consuming. Moreover, this repeated diluent/air exchange procedure under a large pressure gradient, often results in a leak in the rubber stopper cap of the medicament container, which can result in spillage of medicament, which as indicated above, is often toxic, highly irritating and potentially mutagenic to the person preparing the material. This can result in serious injury and in addition, result in wasted and/or inaccurately diluted medicament.